The compositions made use of for occlusion of ducts and cavities of human body must satisfy a number of specific requirements. Such compositions must feature:
1. Biocompatibility
2. Low initial viscosity (under 50 centipoise).
3. Fluidity in the air for at least 10 or 15 minutes and ability to render into solid state within 1 to 3 minutes upon being injected into a duct or cavity.
4. Adhesion to the ductal or cavitary wall.
5. Ability to be destructed and taken out of the organism within one to three months.
6. Radiopacity
7. Antiseptic properties.
Known in the art nowadays are compositions for occlusion of ducts and cavities of human body, based on silicones (cf. a paper by D. F. Blagovidov et al., in the journal `Klinicheskaya khirurgia`, 1982 No. 11, pp. 10-14. These compositions are biocompatible, produce no local irritating effect, retain fluidity in the air for a prolonged period of time, and are radiopaque. However, the aforementioned compositions possess too high viscosity which impedes their injection into ducts or cavities. Besides, the silicone-based compositions are devoid of adhesion to the walls of ducts or cavities, which might result in `expelling` of the preformed plug out of the ducts and in recanalization thereof, as well as in formation of vacant spaces or passages in between the plug and the ductal walls, which makes the surgical procedure ineffective. Prolonged (over 10 minutes) polymerization time upon getting in contact with body tissues adds to complexity involved in handling the silicone-based occluding compositions, might result in back flowing of such a composition through the accessory pancreatic duct during surgery and hence in incomplete occlusion of the pancreatic ducts. Silicone-based compositions do not possess antiseptic properties, are incapable of developing biodestruction processes, that is, they turn into alien bodies after having performed their function and might prove to be a focus of infection.
Known in the art is another composition for occlusion of ducts and cavities of human body, based on an alcoholic solution of amino-acids, i.e., Prolamine (otherwise called ethibloc). The composition features low initial viscosity, retains fluidity in the air for a prolonged period of time and possesses radiopacity and antiseptic properties (cf. Gebhardt Ch., Stolte M. Lang. Arch. Chir., 1978, Bd. 346, H. 3, S. 149-166). On the other hand, ethibloc features rather long (15 to 20 minutes) setting period upon setting in contact with human tissues which might lead to backward flow of the composition and hence to no effect of the surgical procedure performed. Furthermore, ethibloc is not adhesive to the ductal walls, which might result in "expulsion' of the thus-formed plug, formation of vacant spaces or passages between the plug and the walls of ducts or cavities and hence in recanalization of the ducts and in no effect of the surgery performed. Too rapid (within 11 to 14 days) destruction of the composition and its elimination from the organism results in recanalization of the pancreatic duct system till the complete atrophy is developed, which in particular, results in some cases of occlusion of pancreatic ducts out in incomplete atrophy of the exocrinous tissue of the pancreas. In addition, ethibloc features as short shelf time as three months which lays additional obstacles to its application.
There are also known compositions for occlusion of ducts and cavities of human body based on quick-polymerizing monomers, namely alpha-cyanoacrylates, in particular, esters of alpha-cyanoacrylic acid (cf. Little J. M., Laner C. Surgery, 1977, v. 81, No. 3, pp. 243-249). Said compositions are in fact low-viscosity liquids quickly polymerizable in thin layer upon getting in contact with body tissues, biocompatible and capable of undergoing biodestruction. There is also known application of compositions based on alpha-cyanoacrylates for occlusion of the pancreatic ducts aimed at embolization of blood vessels. It is common knowledge that cyanoacrylates are capable of polymerizing very rapidly (within a few seconds) on getting in contact with body tissues, which might eventuate in incomplete occlusion of ducts or cavities. Fast polymerization of alpha-cyanoacrylates and their being incapable of polymerizing uniformly in a duct or cavity might result in formation of separate conglomerates of the polymer lengthwise the duct, thus rendering the performed surgery ineffective. In addition, use of cyanoacrylates might lead to sticking of the catheter through which the composition has been injected, to the ductal wall. The fact that cyanoacrylates are devoid of antiseptic properties and radiopacity adds to difficulties in handling such compositions.
Thus, none of the compositions of the character set forth hereinabove and now in current use meets all requirements imposed on materials for occlusion of ducts and cavities of human body.